ROSACEAE

ROSE FAMILY

Annual to tree
Leaves simple to pinnately to palmately compound, generally alternate; stipules free to fused, persistent to deciduous
Inflorescence: cyme, raceme, panicle, or flowers solitary
Flower generally bisexual, radial; hypanthium free or fused to ovary, saucer- to funnel-shaped, often with bractlets alternate with sepals; sepals generally 5; petals generally 5, free; stamens (0)5–many, pistils (0)1–many, simple or compound; ovary superior to inferior, styles 1–5
Fruit: achene, follicle, drupe, pome, or blackberry- to raspberry-like
Seeds generally 1–5
Genera in family: 110 genera, ± 3000 species: worldwide, especially temp. Many cultivated for ornamental and fruit, especially Cotoneaster , Fragaria , Malus , Prunus , Pyracantha, Rosa , and Rubus
Reference: [Robertson 1974 J Arnold Arbor 55:303–332,344–401,611–662]
Family description, key to genera by Barbara Ertter and Dieter H. Wilken.

HOLODISCUS

Richard A. Lis

Shrub, ± hairy
Stem 3–60 dm; bark reddish, in age gray, shredding
Leaves simple, alternate, 0.3–12 cm, thin to leathery, toothed; base truncate to generally ± wedge-shaped; lower surface strongly veined; stipules 0; petiole distinct or not
Inflorescence: panicle, ± terminal, dense, 2.5–25 cm, ± conic, many-flowered, persistent; pedicel slender, bractlets 1–3
Flower: hypanthium 3–5 mm wide, saucer-shaped, prominent nectary-disk below inner rim; sepals 5, 1–2 mm; petals 5, 1.5–2 mm, ± ovate, generally white; stamens 15–20, wider at base; pistils 5, ovaries superior, 2-ovuled, hairs dense, bristle-like, persistent in fruit, style 1 mm, persistent, stigma ± 2-lobed
Fruit: achenes 5, 1–1.5 mm, often with sessile glands
Species in genus: 5 species: w North America, C.Am, n South America
Etymology: (Greek: whole disk)
Spp. highly variable; leaves of peg-like stems best for identification; complexity in c SNH evidently from local climatic variation, hybridization.

Native

H. microphyllus Rydb.

Plant 0.3–1 m, ± dense
Stem: peg-like stems very predominant
Leaves of peg-like stems generally 0.3–2 cm, obovate, others 1–3 cm, ovate to ± round; teeth of 1 size, those of leaves on peg-like stems near tip, rarely to middle, those of others generally to middle; petiole generally indistinct, winged or not
Inflorescence generally mixed with leaves, 2–8 cm, 1.5–5 cm wide
Flower: sepal lower surface glabrous to densely short- to long-hairy, upper surface glabrous
Ecology: Rocky places, outcrops
Elevation: 600–4000 m.
Bioregional distribution: High North Coast Ranges, High Sierra Nevada (2700–4000 m), San Gabriel Mountains (1800–3300 m), San Bernardino Mountains, San Jacinto Mountains, Great Basin Floristic Province, Desert Mountains
Distribution outside California: to Oregon, Idaho, Wyoming, Colorado, Arizona, Baja California
Lvs of peg-like stems from plants of wet places more often ovate to round than obovate.

Native

var. microphyllus

ROCK SPIRAEA

Stem hairy to long-hairy; glands 0 or obscured by hairs
Leaf ± long-hairy on 1 or both surfaces; hairs not greatly longer on margins and veins; glands 0 or often obscured by hairs
Flower: sepals hairy to long-hairy; glands 0
Ecology: Habitats of sp.
Elevation: 1200–4000 m.
Bioregional distribution: High Sierra Nevada (2700–4000 m), San Gabriel Mountains (1800–3300 m), San Bernardino Mountains, San Jacinto Mountains, East of Sierra Nevada, Desert Mountains
Flowering time: Jun–Aug
Synonyms: var. sericeus Ley
Horticultural information: TRY.